a-a a-b a-i a-t aaa aab aai aap aar aas aat ab- aba abb abi abp abr abs abt ai- aia aib aii aip air ais ait ap- apa apb api app apr aps apt ar- ara arb ari arp arr ars art as- asa asb asi asp asr ass ast at- ata atb ati atp atr ats att b-p baa bab bai bap bar bas bat bba bbb bbi bbp bbr bbs bbt bi- bia bib bii bip bir bis bit bpa bpb bpi bpp bpr bps bpt bra brb bri brp brr brs brt bsa bsb bsi bsp bsr bss bst bta btb bti btp btr bts btt ia- iaa iab iai iap iar ias iat iba ibb ibi ibp ibr ibs ibt iia iib iii iip iir iis iit ipa ipb ipi ipp ipr ips ipt ir- ira irb iri irp irr irs irt is- isa isb isi isp isr iss ist ita itb iti itp its itt p-p paa pab pai pap par pas pat pba pbb pbi pbp pbr pbs pbt pia pib pii pip pir pis pit ppa ppb ppi ppp ppr pps ppt pra prb pri prp prr prs prt ps- psa psb psi psp psr pss pst pt- pta ptb pti ptp ptr pts ptt ra- raa rab rai rap rar ras rat rba rbb rbi rbp rbr rbs rbt ria rib rii rip rir ris rit rpa rpb rpi rpp rpr rps rpt rra rrb rri rrp rrr rrs rrt rsa rsb rsi rsp rsr rss rst rta rtb rti rtp rtr rts rtt saa sab sai sap sar sas sat sba sbb sbi sbp sbr sbs sbt sia sib sii sip sir sis sit spa spb spi spp spr sps spt sr- sra srb sri srp srr srs srt ss- ssa ssb ssi ssp ssr sss sst sta stb sti stp str sts stt taa tab tai tap tar tas tat tba tbb tbi tbp tbr tbs tbt tia tib tii tip tir tis tit tpa tpb tpi tpp tpr tps tpt tra trb tri trp trr trs trt tsa tsb tsi tsp tsr tss tst tta ttb tti ttp ttr tts ttt